Subject:
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Re: Stepper vs DC
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Thu, 10 Dec 1998 13:22:18 GMT
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Original-From:
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John Vaughn <vaughn@HWS.EDU>
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Reply-To:
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vaughn@HWS.&avoidspam&EDU
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Viewed:
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985 times
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edmund wrote:
> after reading your mails, it seems to me that the dc motor is better than
> the stepper motor. doesn't the stepper motor offer any advantages over
> the dc motor? is the stepper motor that bad?
>
>
> edmund.
Actually, steppers do have some advantages.
1) If you do not have encoders on DC gearhead motors (or wheels, etc) they are
notoriously hard to position accurately. Steppers can be
controlled very accurately. Most servo motors cannot rotate beyond 180
degrees unless they are mechanically modified, usually disabling
their feedback pots so they have no position sensing.
2) It is hard to hold DC motors in a fixed position (if your robot is headed
uphill on a slope) while steppers can be "locked" in place by keeping
the coils energized.
3) Steppers can be cheaper. Jameco has some small unipolar steppers for $6.
You can dig usable steppers out of old 5 1/4 inch floppy disk drives
for almost nothing. Optically encoded DC motors are rarely very cheap unless
you find remainders, used ones, etc.
4) On the down side, software control of steppers is harder, they require
acceleration code (you cannot just "turn 'em on to 100%") and they tend to be
heavy.
I use both kinds of motors in robots for different tasks.
John Vaughn
vaughn@hws.edu
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Message is in Reply To:
 | | Stepper vs DC
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| after reading your mails, it seems to me that the dc motor is better than the stepper motor. doesn't the stepper motor offer any advantages over the dc motor? is the stepper motor that bad? edmund. (26 years ago, 10-Dec-98, to lugnet.robotics.handyboard)
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